1. Field of the Invention
The invention relates to inflatable devices, such as packers or bridge plugs, for use in subterranean wells.
2. Brief Description of the Prior Art
In the drilling, completion or workover operations of subterranean wells, it often becomes desirable to isolate one section of the well bore from another section of the well bore. In such event, a sealing tool, commonly referred to as a well packer, bridge plug, or the like, is used. Those skilled in the art are well familiar with such tools which have varying configurations.
One type of such well packer is an inflatable well packer which is run in the well on tubing wire line, or the like, and is sealingly engagable with the interior of casing set within the well, or, if the well is not set with casing, with the interior well bore wall, by means of application of well or other fluid under pressure to cause a tubular elastic body to expand radially outwardly. Such bodies are typically reinforced with a reinforcing sheath which has, in turn, secured around its exterior, approximate medial portion, a hardened rubber element which is the packing component, itself. Representative of such configurations can be found in patents assigned to Lynes, Inc., such as U.S. Pat. Nos. 3,604,732, and 3,837,947.
In recent years, some inflatable tools have been provided in designs in which the reinforcing ribs do not carry around their exterior the hardened rubber packer component such that when the apparatus is inflated to set the device within the well bore, the reinforcing component radially expands to act as an anchor against longitudinal and/or rotational movements of the apparatus in the well. In many such configurations, it has been found that the inflation of the tubular elastic body will cause the reinforcing component to radially expand such that the reinforcing component "kinks" as the ribs move outwardly such as do petals of a flower. Also, the inflation of tubular elastic body will cause uneven circumferential overlap of the reinforcing components such that some of the reinforcing components may not overlap as the ribs move outwardly creating an extrusion gap between the reinforcing components. When this occurs, the tubular elastic body will become vulnerable to cutting extrusion and abrasion if it is disposed between ribs during such action, resulting in a loss or decrease in inflation pressure and, in turn, he integrity of the seal established by the setting of the packer at such position within the well bore.
The present invention is directed toward an abatement of such problem by providing an apparatus and method wherein the expansion of the ribs is assisted by means of an expansion control belt surrounding the exterior of the ribs to conform their radial expansion movements.